Hi,

I'm trying to get this YYI-2 current sensing relay module to react to the current going towards my car's alarm siren. This should allow it to emulate the SOS-button of a car gps tracker so I can get a text message when the alarm goes off.

I tried hooking it up now, with the cable (that goes to the siren) I want to measure the current of routed through the load ports, so basically the current comes in on load+, and then it should go out on load- and supply the siren as usual. I realized that the load- port is connected internally to the DC- port (I measured continuity as well), which makes no sense to me. I connected 12V to DC+ and ground to DC-. This means there'll be a short to ground instead of having the current go through load+ to load- and then onwards to the load... How does this make any sense?

I've attached a drawing of how I've connected it, apart from the SOS button cables for simplicity. I've used a fuse thief (like this one: https://cdn11.bigcommerce.com/s-ewn...0121/WSC-83227_Main__51670.1681375811.png?c=2) that allows me to tap into the fuse slot of the siren's fuse, reroute instead through the load ports of the YYI-2 and then back to the fuse slot, so I would be able to measure the current to it, and at the same time, the thief then distributes it not only into the fuse slot that leads to the siren, but also to its second fuse slot where I've put the 7.5A fuse and it then goes out through the cable and is used to provide the tracker and YYI-2 module (in its DC+ port) with 12V.

When I tried hooking it up, one of the fuses, I think it was the 7.5A one in the fuse thief, blew immediately. The YYI-2 screen was on though, and I could set my thresholds and everything. Also, the load ports are not a bypass - there seems to be a complete voltage drop, which is not surprising since the load- and DC- are connected.

There's been a previous thread about this module, and he never got it to work: https://forum.allaboutcircuits.com/...ith-relay-not-reading-correct-current.169102/

Thanks in advance!

 

I'm trying to get this YYI-2 current sensing relay module to react to the current going towards my car's alarm siren.

Your description is confusing.
Do you have a link to the car alarm or a wiring diagram for the alarm?
I see the wiring like this:

 

Sure, here's the diagram for the siren. 701 is the rear fuse box, 707 is the Body Control Module which issues instructions to it. I'm basically trying to measure the current in the power supply to the siren, so I've connected a fuse thief in the slot for fuse 24, leading the current (that would otherwise go through the fuse and then to the siren) to the load+ of the YYI-2, and then back from load- to the second pin of fuse 24, so that all current that goes to the siren has to go through the load ports of the YYI-2 first. Sorry, I realize I forgot to mention in my hand-drawn diagram that from fuse 24, the current also goes to the siren, and the fuse thief allows me to split the returning leg in fuse 24 to also have another wire lead to the power supply of the YYI-2 and the gps tracker. So the YYI-2 would then measure the current to the siren and to the tracker and itself. When the alarm goes off, the current increases by 0.3A, making it a suitable trigger.

The gps tracker is a ST-906L, and the diagram for connecting it can be found here: https://shopcdnpro.grainajz.com/category/365208/2174/a3c3e500aacffa245e4776d05d4f390b/ST-906L接线.jpg
I've routed the SOS-button wires to the NO and COM ports of the YYI-2, so that when the relay triggers, it closes the circuit, simulating pushing the SOS-button.

From your diagram, it looks like you've hooked it up like a volt meter, measuring the potential across the alarm? I may have misunderstood something completely of course, but what I did was to basically route the supplying pin of fuse 24, which has battery voltage i.e. ~12V, to "IN+", and then from "IN-" back to the other pin of fuse 24, leading to the siren, and, thanks to the fuse thief, also split from there to supply the tracker and YYI-2's DC+ pin.

 

Like this:

 

Almost! This is how I did it (the 7.5A fuse is inserted in the second slot of the fuse thief, so it's for the cable that goes out of the fuse thief):

 

With that arrangement I don't see how any current from the alarm can pass through the module.
I see a direct short from ground to 12 volts.

 

The current for the alarm goes through the 24th fuse slot. Now, if my understanding is correct, it should go to IN+, and out through IN- (allowing the YYI-2 to measure the current), and then back to the 24th fuse's second pin and onwards to the alarm siren (as well as the tracker and YYI-2's DC+ that's now in parallel)

 

No the -IN is connected to ground and actually internally connected to -DC on the circuit board which connects to ground.
I believe it should be wired as in my previous post.

 

That's true, and is why I'm so confused. But you're saying that it's measuring the current that comes in through DC+ and that said current then goes out through IN+? So like this then?

And IN- is just redundant since it's connected to DC- anyway? Any idea why they even have it?

 

-IN is just for convenience but since the alarm is already grounded not needed in this situation.
Pin2 of the alarm connects to +IN only with or without the 10 amp fuse. The +DC terminal back to the fuse box as I show in post #4.

 

All right, thank you so much, I'll give this a try today or tomorrow and let you know how it worked out!

 

It seems to be working! Triggering the alarm makes the module's display show a higher current and it looks to be triggering the relay as well since there was a red light showing up. I still don't know if the tracker will send a text message since I'm out of the country and I have to activate the sim card for foreign operation, but probably will work.